A destination; the place someone or something is going to (common in travel/movement contexts).
電車の行き先を確認してから乗ってください。
Please check the train's destination before getting on.
荷物に行き先を書いておいた。
I wrote the destination on the luggage.
旅行の行き先はまだ決めていない。
I haven't decided on the travel destination yet.
Whereabouts; the place someone or something is headed or has gone (used for asking/indicating where someone is or will be).
子どもの行き先を親に知らせておきなさい。
Tell your parents where you are going.
彼の行き先が分からなくなったので、警察に届けた。
His whereabouts became unknown, so we reported it to the police.
Future prospects or outlook; the future direction of a career, company, or project.
大学卒業後の行き先について家族と話し合った。
I discussed my plans after graduating from university with my family.
会社の行き先が不透明で、不安を感じている社員もいる。
Some employees feel uneasy because the company's future direction is unclear.